Method for monitoring a state of a container or container component, and inspection system

Abstract

Method and inspection system for monitoring a state of a container (110) adapted and configured to hold wafers or reticles, the container comprising a body (115), a lid (120) and a gasket (122) provided on the body (115) or on the lid (120), the gasket (122) being configured and adapted to ensure a gas-tight seal between the body (115) and the lid (120) in order to provide a closed space within the container (110), which is gas-tightly sealed relative to an outside environment, the method comprising imaging the gasket (122) against a background (106), wherein the gasket (122) and the background (106) are provided with different colours and / or are provided with different patterns.

Description

[0001] Method for monitoring a state of a container or container component, and inspection system

[0002] Description

[0003] The application relates to a method and an inspection system for monitoring a state of a container adapted and configured to hold wafers or reticles or a container component, the state of the container including the state of a gasket.

[0004] Reticles are photomasks used for the production of integrated circuits, so called chips, to produce patterns on thin wafers of material, usually silicon.

[0005] Cleanliness requirements within the semiconductor industry has become ever more important, especially in connection with EUV technology. In order to obtain a reasonable yield of chips, the entire fabrication and handling environment for reticles and semiconductor wafers, sometimes referred to as semiconductor ecosystem, needs to work at extreme levels of efficiency and cleanliness with almost no scope for error. This requirement necessitates monitoring every aspect of the semiconductor ecosystem, irrespective of it belonging to manufacturing, process control or R&D. Every piece of information thus generated and stored can prove invaluable.

[0006] Contamination control plays an especially crucial role, as this directly influences cleanliness of wafers. Wafers are typically transported in specialized containers, so called FOURS (Front Opening Unified Pods), and the environment within these containers, often referred to as mini environment, is critical, as it directly impacts wafer or chip yield. This chip yield can be significantly enhanced by appropriate contamination control. Contamination control also plays a crucial part in connection with reticle storage pods, often referred to as RSPs

[0007] In semiconductor manufacturing, the trend towards smaller features-approaching that of atomic-scale-has brought with it new challenges. One is the challenge of controlling airborne molecular contaminants (AMC). AMC come from both internal processes such as chemicals and materials used in the manufacturing of containers and external processes, such as the air supply within semiconductor fabs. The presence of AMC even at very low concentrations can lead to costly defects in the wafers or reticles. Water vapor or moisture within containers is also to be avoided. Moisture can induce various chemical reactions that subsequently lead to defects. Currently, moisture contamination control is adopted in many wafer handling and storage situations. Particles, AMC, oxygen, and moisture have the potential to cause defects on reticles or wafers which can lead to reduced product performance or product yield in manufacturing processes.

[0008] FOUPs are typically made of polycarbonate material, which is a hygroscopic polymer that can retain moisture. This means that cleaning fluids such as deionised water can be absorbed during the cleaning process. On the other hand, subsequent purging, for example using clean dry air (CDA), can induce desorption of moisture from the FOUP material. Hereafter, it must be ensured that FOUPs thus cleaned are completely free of moisture before usage. The capability of a FOUP to retain moisture can change over time, giving an indication of its age and condition.

[0009] Reticles, for which similar if not even more stringent cleanliness requirements apply, are usually transported and stored in RSPs, as mentioned above. RSPs and FOUPS will be at times simply referred to as ‘pods’ or containers in the following.

[0010] These specialised containers for holding wafers or reticles typically comprise a body member (“body”), also referred to as “shell”, which defines an internal space, and a lid member (“lid”), which can be sealingly connected to the body by means of a rubber gasket or seal provided on the body and / or the lid, thereby defining a closed and sealed state of the container, so that e.g. a controlled environment can be provided within the container. The lid member can be opened and / or disconnected from the body in order to load or unload the container. Typically, a so-called lid opener, typically comprising a lid opener plate, is used to remove and replace the lid relative to the body. On at least two opposite interior surfaces, the body is typically provided with a number of parallel grooves or ridges adapted to stack a number of wafers or reticles securely and safely in the container, without them touching one another. Seals and gaskets must be replaced regularly in order to be able to guarantee a closed and sealed environment within the container (pod). Ascertaining the condition of gaskets also gives useful information as to the condition of the container as a whole.

[0011] In semiconductor wafer processing, robotic mechanisms are constantly arranging, moving, transporting, organizing, and processing wafers and wafer containers, such as a front opening unified pod (FOUR). The FOIIP or one of its components such as a gasket may be damaged in the process (e.g. scratch, break, deform, etc.), which may also lead to damage to wafers being stored or transported in such FOUPs.

[0012] FOUPs and RSPs provide a gas-tight space for wafers and reticles respectively, such that these wafers or reticles can be protected from contamination present in a surrounding environment. To ensure gas-tightness, a gasket is provided between body and lid, as discussed.

[0013] Furthermore, FOUPs and RSPs are subject to normal wear and tear. For example, a gasket / seal provided between the body and the lid in order to maintain an uncontaminated environment within the FOUP or the RSP can become damaged or brittle over time, or can be subject to shrinkage, such that its sealing capacity is diminished. This gasket requires maintenance, and it must be ensured that it is not subjected to excessive wear and tear, which could lead to its sealing capabilities being compromised. Seals and Gaskets are thus inspected, usually on a regular basis.

[0014] There exists a need to efficiently inspect the wafer or reticle containers such as FOUPs or RSPs for this kind of damage and / or defects. Also, the dimensions of such containers or their components, such as gaskets, which can vary over time, for example due to material shrinkage, are critical, and have to meet certain specifications.

[0015] Inspection systems for FOUPs are disclosed for example in WO 2016 / 139249 A1 . It is desirable to be able to easily identify containers or their components, especially seals or gaskets, that are damaged and / or do not meet said specifications and / or are contaminated, so that such containers can be effectively removed from the manufacturing cycle of wafers or reticles. On the other hand, it is also desirable to use such containers for as long as possible in order to minimise investment costs and use of natural resources.

[0016] The present invention proposes a method of monitoring the state of a container comprising the features of claim 1 and a corresponding inspection system comprising the features of claim 6.

[0017] According to the invention there is provided a method for monitoring a state of a container adapted and configured to hold wafers or reticles, the container comprising a body, a lid and a gasket provided on the body or on the lid, the gasket being configured and adapted to ensure, when the lid is attached to the body, a gas-tight seal between the body and the lid to provide a closed space within the body, which is gas-tightly sealed relative to an outside environment, comprising imaging the gasket against a background, wherein the gasket and the background are provided with different colours and / or are provided with different patterns. The terms “different colours” and / or “different patterns” shall especially mean that the gasket comprises a surface region having a first visually differentiable characteristic selected from the group consisting of a first colour and a first pattern, and the background comprises a surface region having a second visually differentiable characteristic different from the first characteristic, selected from the group consisting of a second colour and a second pattern.

[0018] The different colours and / or patterns, especially visual patterns, are adapted or chosen / set such that imaging, especially using contour extraction methods, is facilitated and / or enhanced. If the gasket is provided on the body, it is typically formed in an engagement section of the body formed by the edge of the body at its open side, i.e. the side which is then closed by attaching the lid. If the gasket is provided on the lid, a gasket engagement section of the lid is typically formed by a peripheral section of the lid which is provided to face the edge of the body at the open side of the body.

[0019] According to a preferred embodiment, the background is provided by a lid opener or lid opener plate, which serves to remove the lid from the body of the container. Alternatively, the background is provided by a container, in which the imaging is performed. Be it noted that the background might also be provided by the gasket engagement section of the body or the lid, on which the gasket is formed. For example, if the gasket is not provided at the outermost circumference of the lid, i.e. in such a way that a narrow peripheral section is formed between the gasket and the edge of the lid, this narrow peripheral section can be used as the background for imaging the gasket.

[0020] Advantageously, the monitoring comprises evaluation of the state of the container based on the imaging. By providing the gasket and the background in different colours and / or with different patterns, imaging can be performed in a more reliable way than according to prior art solutions.

[0021] Expediently, the imaging is performed using a high-resolution camera and a contour extraction unit. Contour extraction is enhanced and facilitated in case the gasket and the background are provided with different colours and / or with different patterns.

[0022] Contour extraction using a high-resolution camera is a fundamental technique for monitoring and analysing the shape of an item with high precision. This process involves capturing detailed images of the item by means of a camera, wherein the high resolution of the camera ensures that even minute features and subtle variations in the item's outline are clearly represented. The captured image is then subjected to image processing algorithms that segment the item from its background and detect the boundaries where the item meets or borders on the surrounding environment. Contour extraction methods systematically trace these boundaries, converting them into digital data that represent the exact shape of the component. Contour extraction methods typically identify transition points along scanning lines in the image, corresponding to the edges of the item. These points are systematically linked to form a continuous contour that accurately traces the outer boundary of the item.

[0023] By converting these transition or boundary points into coordinate data, the system can quantitatively analyse the shape and detect any deformations or irregularities. The extracted contour data can be further processed for various applications, such as quality control, defect detection, or dimensional verification, providing a reliable and automated means of monitoring the physical characteristics of items, especially in real time. Such contour data as thus measured / imaged can then especially be compared to target data, for example corresponding to the item being imaged in its new and fully functional state. Depending on how much measured / imaged data digress from the target data, the state of the item being imaged can be ascertained or evaluated.

[0024] This approach leverages the advantages of high-resolution imaging to achieve robust and detailed contour detection, enabling enhanced accuracy in shape monitoring compared to lower-resolution or manual inspection methods.

[0025] Contour extraction using a high-resolution camera especially provides a precise and automated method for monitoring the shape of rubber or plastics components such as gaskets or seals. Such rubber components require careful quality control due to their elastic and resilient properties, as well as their tendency to deform under stress or during manufacturing, or to shrink as they age. The invention helps to monitor such rubber components which have a flexible nature and complex shapes, demanding a high level of detail and accuracy in inspection.

[0026] It is especially advantageous to vary the colour and / or the pattern of at least one of the items gasket, background and engagement section by exposure to heat or voltage or any other suitable colour changing influence. In other words, the materials which these items are made of advantageously are provided with chromogenic properties. A material may exhibit a change in optical properties, such as colour, in response to an external stimulus. This behaviour is generally referred to as chromogenic behaviour, and the underlying material property is known as chromogenicity. Depending on the type of stimulus applied, different forms of chromogenicity may be distinguished. For example, thermochromicity refers to the reversible or irreversible change in colour of a material in response to variations in temperature. Electrochromicity denotes a colour change induced by the application of an electric potential, while photochromicity describes colour changes triggered by exposure to electromagnetic radiation, typically in the ultraviolet or visible range. Hereby, the method and an inspection system performing the method can be easily adapted to provide specific colours of the gasket and / or the engagement section and / or the background, by exposing any of these items to expediently chosen voltage, heat or electromagnetic radiation. For example, if the state of a dark or black gasket is to be evaluated, it would be advantageous to expose the background, which under conditions not exposed to a voltage or temperature or electromagnetic radiation is also dark or black, especially the lid opener, to a voltage or a temperature or electromagnetic radiation by which its colour is changed to a lighter shade. Herby, imaging, especially contour extraction, can be enhanced and / or facilitated.

[0027] The invention also provides an inspection system for monitoring a state of a container adapted and configured to hold wafers or reticles, comprising an inspection chamber provided with a high-resolution camera and an evaluation unit comprising a contour extraction unit, by means of which the method according to the invention including any of the preferred embodiments can be performed. The contour extraction unit is especially adapted to perform contour extraction as discussed above.

[0028] Other features or components of a container which can be imaged and inspected according to the invention include slots, diffusors, filters, door retainers, grommets, doors, handling features, flanges container handles, especially FOUR or RSP handles. Also, wafers or other objects stored in the container can be imaged in this way. Advantageously, a comparison of an imaged and thus measured contour extraction of the gasket with a nominal contour of a gasket, e.g. of a gasket in new condition, is performed, and a deviation between the imaged / measured contour and the nominal contour is determined. Depending on the amount and / or type of deviation, an evaluation of the state of the feature or component, i.e. the gasket, and thus of the state of the container can be made. The deviation determined in this way may comprise a maximum deviation, comparing the positions of individual points of a contour, or an integral deviation determined over a complete contour. For example, a deviation in a length of a contour can be determined, and if this deviation is larger than 1 % , 2%, 3%, 5% or 10% of the length, it can be determined that the feature or component, with which this contour is associated, and / or the container as a whole, requires replacement or maintenance.

[0029] In other words, the invention especially considers adapting the background used in imaging as discussed above, especially provided as a lid opener or a background of a chamber, in which FOUR or RSP inspection is performed, in order to provide enhanced detection and contrast so that the FOUR or RSP contours can be detected with more precision and / or in a faster way. Previously, for example, FOUPs were only provided in a few colours, but over time this has changed and FOUPs are provided in many different colours. This poses a huge challenge in terms of image processing as the cameras are often black and white cameras with gradations of grey levels (GL). Colour variations lead to GL variations, which compromises detectability of defects on the FOUP. This is addressed by the present invention.

[0030] One of the ways to attend to this problem is to provide a ‘chameleon background’ as discussed above, wherein the background colour can be varied based on the FOUP or gasket colour to provide a standard and sufficient GL difference for the algorithm to be able to detect features and defects. This could be achieved in multiple ways, for example by providing the background with contrasting colour, or using an adaptive background that can change colours based on voltage or temperature or other controllable means, as discussed. The invention will now be further described referring to the accompanying drawings.

[0031] Herein

[0032] Figure 1 schematically shows a preferred embodiment of an inspection system according to the invention,

[0033] Figure 2 shows a schematic top view of a lid of a FOUR in a state of being handled by a lid opener plate, wherein the lid is provided with a gasket in a non-contrasting colour,

[0034] Figure 3 shows a schematic top view of a lid of a FOUR in a state of being handled by a lid opener plate, wherein the lid is provided with a gasket in a contrasting colour, according to an embodiment of the invention.

[0035] Figure 4 shows a schematic top view of a lid of a FOIIP in a state of being handled by a lid opener plate, wherein the lid opener is provided with an embodiment of a patterned surface, according to an embodiment of the invention,

[0036] Figure 5 shows a schematic top view of a lid of a FOIIP in a state of being handled by a lid opener plate, wherein the lid opener is provided with a further embodiment of a patterned surface, according to an embodiment of the invention,

[0037] Figure 6 shows a schematic top view of a lid of a FOIIP in a state of being handled by a lid opener plate, wherein a dedicated lighting unit is provided adapted to selectively illuminate at least one of the items lid, lid opener plate or gasket, according to an embodiment of the invention, and

[0038] Figure 7 shows a schematic top view of a lid of a FOIIP in a state of being handled by a lid opener plate, wherein a dedicated lighting unit is provided adapted to selectively illuminate at least one of the items lids, lid opener plate or gasket, according to an embodiment of the invention. In Figure 1 , a preferred embodiment of an inspection system according to the invention is shown and generally designated 100. The inspection system 100 is designed for inspecting a FOUR 110 comprising a body or shell 115 and a lid 120. The system comprises an inspection chamber 102 equipped with a camera 150. Camera 150 is especially provided as a high-resolution camera and is connected to an evaluation unit 152 that processes and analyses the images captured by the camera 150 to assess the integrity and / or cleanliness of the FOUR. The evaluation unit is provided with a contour extraction unit 154.

[0039] The inspection chamber 102 according to the embodiment of Figure 1 provides a controlled environment to ensure consistent image acquisition. The FOIIP 110 is placed within this chamber 102, which may include features such as automated loading and unloading mechanisms (not shown) compatible with semiconductor fabrication automation systems. Within chamber 102, high-resolution camera 150 is mounted and configured to capture detailed images of critical FOIIP components, including the interior and exterior surfaces, door mechanisms, purge ports, and wafer slots. The camera 150 is specifically adapted to provide an image of the lid 120 of the FOIIP, which typically comprises a gasket 122, as indicated by dashed lines. Gaskets are typically made of high-purity, low-outgassing elastomeric materials that are compatible with ultra-clean environments of semiconductor fabrication. Examples are perfluoroelastomers, fluoroelastomers and silicone rubber.

[0040] The camera 150 is advantageously adapted for capturing images with a resolution of at least 12 megapixels and a pixel size of 1 .5 pm or smaller. The camera 150 is typically equipped with a macro or telecentric lens system. It enables detailed imaging of critical FOIIP features, including gaskets or seals provided on the body 115 or the lid 120 of a FOIIP 110, kinematic pins, and inner surfaces, to detect defects, contamination, or mechanical wear with a spatial accuracy better than 50 pm. Camera 150 is displaceable in various linear and / or rotational directions, as schematically indicated by arrows 160. The camera 150 may support various imaging modalities, such as brightfield and darkfield observation, to enhance defect detection capabilities. According to the embodiment of Figure 1 , there is also provided an illumination means 130 for illuminating the interior of the inspection chamber. This illumination unit may be provided with additional illumination 132 adapted to selectively illuminate for example regions of the lid 120 or the body 115 of FOUR 110. Additional illumination 132 may especially be adapted to selectively illuminate a gasket 122 provided on lid 120.

[0041] To facilitate inspection of FOUR 110, the lid 120 is removeable from body 115 and then held in place within inspection chamber 102 by a lid opener 104 provided with a lid opener plate 106, that is provided within the inspection chamber 102, ensuring that the gasket 122 and other lid components or sections are clearly visible and accessible for inspection by the camera 150.

[0042] During inspection, the lid opener 110 disengages the lid 120 from the body 115 and holds the lid 120, for example by engaging with specific locking features on the lid, such as lock sections and pins (not specifically shown). The lid is securely held by the lid opener plate 106, for example using an absorption or gripping mechanism, so it remains detached from the body 110 during inspection. This arrangement ensures that the lid 120, including the gasket 122, is exposed and accessible for imaging and evaluation, while preventing it from falling or moving during the inspection process. The body 115 or the FOIIP may be securely held within chamber 102 by a dedicated holding mechanism 108. The lid opener 104 and the holding mechanism can be adapted to displace the lid 120 and the body 115 respectively, for example to ensure optimal and variable exposure to camera 150 for inspection from different angles and / or distances.

[0043] The evaluation unit 152, which is provided as an electronic processing system connected to the camera 150, receives image data from the camera 150 and performs automated analysis to detect physical damage, contamination, misalignment, or other defects in the FOIIP, including defects or contamination of lid 120 and gasket 122. The evaluation unit 152 comprises contour extraction unit 154, which is especially adapted to identify contours, such as those of the gasket 122. Herein, advanced image processing algorithms are employed, and the results are stored locally or transmitted to a manufacturing execution system for further action.

[0044] The inspection process can be initiated automatically upon loading of FOUR 110, or manually via a user interface. The camera 150 is adapted to capture images of the FOUR 110, especially of lid 120, from multiple angles, taking into account specific regions of interest, including the lid 120 and the gasket 122 while held by the lid opener plate 106. The evaluation unit 152 may be adapted to analyse the images in real time, identifying defects such as cracks, contamination, or improper assembly. As will be discussed in the following, the lid opener plate 106 can advantageously serve to provide a contrasting background for the gasket 122 during imaging with camera 150.

[0045] Fig. 2 schematically illustrates an example arrangement for imaging a lid 120 of a FOIIP handled by an opener plate 106 serving as a background in the context of the imaging. The opener plate 106 is typically provided in an inspection chamber in a fab environment, as for example described above with reference to Figure 1 . Such inspection chambers allow operators to visually inspect FOUPs for damage, contamination or other issues. More advanced chambers, which are especially useful in the context of the present invention, are configured for automated inspection. The opener plate 106 serves to separate the lid 120 of the FOIIP from a body of the FOIIP (not shown in Figure 2).

[0046] The lid 120 comprises a gasket 122 which extends along at least part of its perimeter and defines a contour of the lid 120 with respect to the opener plate 106. In the illustrated example, the gasket 122 is provided as a narrow strip along the outer edge of the lid 120. The lid 120, the opener plate 106, and the gasket 122 are shown as having the same or similar colours, symbolised by identical or closely matching hatch patterns. This illustrates the imaging challenge addressed by the present invention: the optical contrast between opener plate 106, lid 120, and gasket 122 is insufficient for reliable contour detection in a camera image taken by a camera from a position relative to lid 120 and gasket as for example shown in Figure 1a. In practice, this can lead to indistinct or blurred transitions in the captured image. Figure 2 illustrates the optical imaging of the lid 120, especially of the gasket 122. The lid is positioned on opener plate106. This is typically achieved by using a camera, which is arranged to acquire an image of the opener plate 106, the lid 120 and the gasket 122 from a defined viewing direction. A preferred viewing direction is illustrated in Figure 1 , i.e. an optical axis of camera 150 extending orthogonally to the background plate, or under a predetermined angle. In the view of Figure 2, as well as of the further Figures, it is thus assumed that the camera is arranged above items 106,120 and 122, and captures images essentially in the drawing plane, in and around which items 106, 120 and 122 are arranged.

[0047] The camera is operated to acquire at least one image of the opener plate 106 and of the lid 120 located thereon. The acquired image is subsequently evaluated by an evaluation unit, for example evaluation unit 152 as shown in Figure 1 , in order to determine geometric parameters of the lid 120, especially of the gasket 122, such as its position, orientation, or its dimensions. Especially, the image of the gasket 122 (i.e. measured data), which can be subject to defects, for example shrinkage or other forms of wear and tear, shall be compared to a reference image of a new and fully functional gasket (i.e. target data).

[0048] Good imaging results rely on the ability of the imaging system, i.e. the camera and corresponding evaluation units, to distinguish the lid 120 and the gasket 122 from the background, for example provided by opener plate 106. Difficulties arise when the opener plate 106, the lid 120, and the gasket 122 all have substantially the same colour or optical appearance, as shown in the example according to Figure 2, such as the same reflectance or chromatic properties under the illumination conditions used for imaging.

[0049] In such cases, the contours of the lid 120, including those of the gasket 122, are poorly resolved in the image. The transitions between the background (i.e. the opener plate 106) and the lid 120, and between the lid 120 and its gasket 122, become indistinct or invisible to the imaging system. As a result, even automated image processing algorithms may fail to detect the true contour of the lid 120, especially of the gasket 122, leading to inaccurate or unreliable determination of its position and geometry, and thus of its state. Furthermore, artefacts and noise may be introduced in the image segmentation process due to the lack of sufficient contrast.

[0050] To mitigate this difficulty, it is advantageous to provide opener plates, lids, and gaskets with distinct and optically contrasting colours, as shown in Figure 3. Here, according to a first embodiment of the invention, the opener plate 106, the lid 120 and the gasket 122 are provided in contrasting colours and / or grey shades, as indicated by the different hatch patterns. For example, the lid 120 and the opener plate 106 may be provided in darker shades of grey or black, while the gasket 22 is provided in a lighter shade of grey or white. Contrasting colours, such as for example yellow and blue, are also advantageously chosen for the various items as discussed. The most important contrast in this connection is between the gasket 122 and the lid opener 106, in order to easily be able to detect the outer edge of gasket 22. In order to optimally image items 106, 120 and 122 provided with said contrasts, a high- resolution camera is provided, advantageously arranged in the same manner as camera 150 described above with reference to Figure 1. The images captured by this camera are processed by means of an evaluation unit comprising a contour extraction unit, as also discussed in connection with Figure 1 .

[0051] Further embodiments of the invention will now be described in connection with Figures 4 and 5. Be it noted that a high-resolution camera as well as an evaluation unit comprising a contour extraction unit are advantageously also provided in the embodiments of Figures 4 and 5.

[0052] In Figure 4, the opener plate 106 is provided with a section 107 provided with a pattern, for example a hatched pattern as indicated in Figure 4, although other patters are also conceivable. The patterned section 107 is dimensioned to cover a slightly larger area than the lid 120, such that the outer edge of gasket 122 is, in the view of Figure 4, fully surrounded by section 107. The pattern of section 107 may comprise a dark shade of grey or a dark colour, and a light shade of grey or colour, especially black and white. In this case, a favourable contrast between section 107 and gasket 122 for optimising imaging and contour extraction can be provided for gaskets with colours over a large range of shades or colours. For example, if the pattern of section 107 comprises black and white, the gasket 122 could be either black or white, in both cases a sufficient contrast to section 107 would be provided. Patterns with clear differences in brightness, colour or texture between regions make contour extraction more effective. It is noted that also patterns with regular shapes, such as circles, rectangles or polygons with well-defined boundaries are easier for contour extraction algorithms to process.

[0053] In Figure 5, section 107, as discussed above with reference to Figure 4, is provided with a striped pattern comprising darker and lighter colours or shades. The stripes are essentially arranged to extend in a radial direction relative to the lid 120 or the gasket 122. A pattern as shown in Figure 5 has proved to be especially advantageous for precise imaging and contour extraction in the corner sections of the gasket. The line pattern as provided in this embodiment provides an example for long, continuous contours, which are less affected by noise and can provide more stable extraction, as algorithms performed by a contour extraction unit can often more easily process longer, uninterrupted lines.

[0054] It is noted that the contrast provided by section 107 of the opener plate 106 may also be achieved by providing section 107 in an expedient colour. For example, if it is to be assumed that the gaskets 122 will be provided in a first colour, for example blue, it would be expedient to provide section 107 of the opener plate 106 in the complementary colour to the first colour, i.e. yellow, and vice versa.

[0055] According to the embodiment of Figure 6, additional lighting 132, illustrated, purely as an example, by a plurality of LEDs 132, is provided to selectively illuminate opener plate 106, or at least the section of the opener plate 106 surrounding the gasket 122. This additional lighting 132 corresponds to that as discussed with reference to Figure 1 above. By illuminating the opener plate106 in this way, the contrast between the opener plate 106 and the gasket 122 can be increased, thereby improving imaging by, for example, facilitating contour extraction. This additional lighting 132 can be selectively turned on and off, taking into account for example, whether the gasket 122 to be imaged is of a light or a dark shade or colour. The additional lighting 132 could also be used to selectively illuminate other items as discussed, for example gasket 122. Other lighting or illumination techniques can, additionally or alternatively, also be employed, such as structured illumination, illumination making use or polarisation, or differential imaging.

[0056] In Figure 7, further additional lighting is provided to be able to illuminate the items as discussed, especially the gasket 122, from different directions. As a preferred example, the additional lighting according to Figure 7, which is again illustrated, by way of example, as a plurality of LEDs 132, can be provided to illuminate the lid 120 from four sides. The additional lighting can be provided to obliquely illuminate the items in question, i.e. at an angle smaller than a right angle. This additional lighting can also be selectively turned on and off, taking into account for example, whether the gasket to be imaged is provided with a light or a dark shade or colour.

[0057] By applying the imaging techniques as outlined above, faulty or contaminated FOUPs can be effectively identified and isolated, and alerts generated for corrective action. Inspection results and image data are stored and can be transferred to external systems for quality control and traceability.

[0058] This invention ensures that only FOUPs meeting integrity and cleanliness standards are used in wafer processing, reducing the risk of yield loss due to contamination or mechanical failure. It provides rapid, automated, and repeatable inspection, increasing throughput and reliability compared to manual inspection methods. The system also supports integration with factory automation and manufacturing execution systems for seamless operation within semiconductor manufacturing environments.

Claims

Claims1 . Method for monitoring a state of a container (110) adapted and configured to hold wafers or reticles, the container comprising a body (115), a lid (120) and a gasket (122) provided on the body (115) or on the lid (120), the gasket (122) being configured and adapted to ensure a gas-tight seal between the body (115) and the lid (120) in order to provide a closed space within the container (110), which is gas-tightly sealed relative to an outside environment, the method comprising imaging the gasket (122) against a background (106), wherein the gasket (122) and the background (106) are provided with different colours and / or are provided with different patterns.

2. Method according to claim 1 , wherein the background (106) is provided by a lid opener (104) adapted to remove the lid (120) from the body (115), or by an inspection chamber (102), in which the imaging is performed.

3. Method according to claim 1 or 2, wherein the monitoring comprises evaluation of the state of the container (110).

4. Method according to any one of the preceding claims, wherein the imaging is performed using a high-resolution camera (150) and an evaluation unit (152) comprising a contour extraction unit (154).

5. Method according any one of the preceding claims, comprising varying the colour and / or the pattern of the gasket (122) and / or the background (106) by exposure to heat or voltage or any other suitable colour changing influence.

6. Inspection system for monitoring a state of a container (110) adapted and configured to hold wafers or reticles, comprising an inspection chamber (102) provided with a high-resolution camera (150) and an evaluation unit (152) comprising a contour extraction unit (154) configured and adapted to perform the method according to any of the preceding claims..

7. Inspection system according to claim 6, provided with additional lighting (132) for selectively illuminating any one of the background (106), the lid (120) or the gasket (122).

8. Inspection system according to claim 7, wherein the additional lighting (132) can be selectively turned on and off depending on the shade or colour of the background (106), the lid (120) and / or the gasket (122).

9. Inspection system according to claim 7 or 8, wherein the additional lighting (132) is adapted to illuminate the background (106), the lid (120) and / or the gasket (122) from a multitude of directions, especially from four directions.

10. Inspection system according to any one of claims 6 to 9, wherein the camera (150) is adapted to capture images with a resolution of at least 12 megapixels and a pixel size of 1.5 pm or smaller.

Images